EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 474/2 Article
Free access article

Issue A&A
Volume 474, Number 2, November I 2007
Page(s) 565 - 573
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20077953



A&A 474, 565-573 (2007)
DOI: 10.1051/0004-6361:20077953

The spin axes orbital alignment of both stars within the eclipsing binary system V1143 Cyg using the Rossiter-McLaughlin effect

S. Albrecht1, S. Reffert2, I. Snellen1, A. Quirrenbach2, and D. S. Mitchell3

1  Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
    e-mail: albrecht@strw.leidenuniv.nl
2  ZAH - Landessternwarte, Königstuhl 12, 69117 Heidelberg, Germany
3  California Polytechnic State University, San Luis Obispo, CA 93407, USA

(Received 25 May 2007 / Accepted 30 July 2007)

Abstract
Context.The Rossiter-McLaughlin (RM) effect, a rotational effect in eclipsing systems, provides unique insight into the relative orientation of stellar spin axes and orbital axes of eclipsing binary systems.
Aims.Our aim is to develop a robust method to analyze the RM effect in an eclipsing system with two nearly equally bright components. This gives access to the orientation of the stellar rotation axes and may shed light on questions of binary formation and evolution. For example, a misalignment between the spin axes and the angular momentum of the system could bring the observed and theoretical apsidal motion into better agreement for some systems, including V1143 Cyg.
Methods. High-resolution spectra have been obtained both out of eclipse and during the primary and secondary eclipses in the V1143 Cyg system, using the 0.6 m Coudé Auxiliary Telescope (CAT) and the high-resolution Hamilton Echelle Spectrograph at the Lick Observatory. The Rossiter-McLaughlin effect is analyzed in two ways: (1) by measuring the shift of the line center of gravity during different phases of the eclipses and (2) by analysis of the line shape change of the rotational broadening function during eclipses.
Results. We measured the projection of the stellar rotation axes using the rotation effect for both main-sequence stars in an eclipsing binary system. The projected axes of both stars are aligned with the orbital spin within the observational uncertainties, with the angle of the primary rotation axis $\beta_{\rm p}=0.3\pm 1.5^{\circ}$, and the angle of the secondary rotation axis $\beta_{\rm s}=-1.2\pm 1.6^{\circ}$, thereby showing that the remaining difference between the theoretical and observed apsidal motion for this system is not due to a misalignment of the stellar rotation axes. Both methods utilized in this paper work very well, even at times when the broadening profiles of the two stars overlap.


Key words: stars: individual: V1143 Cyg -- binaries: eclipsing -- techniques: spectroscopic -- methods: data analysis -- binaries: spectroscopic



© ESO 2007


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.